CVE-2022-49767
9p/trans_fd: always use O_NONBLOCK read/write
- Published
- Updated
- Reserved
- Assigned by
- Linux
Description
In the Linux kernel, the following vulnerability has been resolved: 9p/trans_fd: always use O_NONBLOCK read/write syzbot is reporting hung task at p9_fd_close() [1], for p9_mux_poll_stop() from p9_conn_destroy() from p9_fd_close() is failing to interrupt already started kernel_read() from p9_fd_read() from p9_read_work() and/or kernel_write() from p9_fd_write() from p9_write_work() requests. Since p9_socket_open() sets O_NONBLOCK flag, p9_mux_poll_stop() does not need to interrupt kernel_read()/kernel_write(). However, since p9_fd_open() does not set O_NONBLOCK flag, but pipe blocks unless signal is pending, p9_mux_poll_stop() needs to interrupt kernel_read()/kernel_write() when the file descriptor refers to a pipe. In other words, pipe file descriptor needs to be handled as if socket file descriptor. We somehow need to interrupt kernel_read()/kernel_write() on pipes. A minimal change, which this patch is doing, is to set O_NONBLOCK flag from p9_fd_open(), for O_NONBLOCK flag does not affect reading/writing of regular files. But this approach changes O_NONBLOCK flag on userspace- supplied file descriptors (which might break userspace programs), and O_NONBLOCK flag could be changed by userspace. It would be possible to set O_NONBLOCK flag every time p9_fd_read()/p9_fd_write() is invoked, but still remains small race window for clearing O_NONBLOCK flag. If we don't want to manipulate O_NONBLOCK flag, we might be able to surround kernel_read()/kernel_write() with set_thread_flag(TIF_SIGPENDING) and recalc_sigpending(). Since p9_read_work()/p9_write_work() works are processed by kernel threads which process global system_wq workqueue, signals could not be delivered from remote threads when p9_mux_poll_stop() from p9_conn_destroy() from p9_fd_close() is called. Therefore, calling set_thread_flag(TIF_SIGPENDING)/recalc_sigpending() every time would be needed if we count on signals for making kernel_read()/kernel_write() non-blocking. [Dominique: add comment at Christian's suggestion]
Timeline
ID reserved
By Linux
- 15 days later
· 15 days later
Published
- 13 months later
· 13 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Analyzed | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.20% · top 90% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected 27979bb2ff748613dba96ae66392a76fb0678527 – < 0b5e6bd72b8171364616841603a70e4ba9837063
- affected 27979bb2ff748613dba96ae66392a76fb0678527 – < 9f8554615df668e4bf83294633ee9d232b28ce45
- affected 27979bb2ff748613dba96ae66392a76fb0678527 – < 7abf40f06a76c0dff42eada10597917e9776fbd4
- affected 27979bb2ff748613dba96ae66392a76fb0678527 – < b1ad04da7fe4515e2ce2d5f2dcab3b5b6d45614b
- affected 27979bb2ff748613dba96ae66392a76fb0678527 – < a8e2fc8f7b41fa9d9ca5f624f4e4d34fce5b40a9
- affected 27979bb2ff748613dba96ae66392a76fb0678527 – < 0e07032b4b4724b8ad1003698cb81083c1818999
- affected 27979bb2ff748613dba96ae66392a76fb0678527 – < 5af16182c5639349415118e9e9aecd8355f7a08b
- affected 27979bb2ff748613dba96ae66392a76fb0678527 – < ef575281b21e9a34dfae544a187c6aac2ae424a9
- affected 2.6.17
- unaffected < 2.6.17
- unaffected 4.9.334 – ≤ 4.9.*
- unaffected 4.14.300 – ≤ 4.14.*
- unaffected 4.19.267 – ≤ 4.19.*
- unaffected 5.4.225 – ≤ 5.4.*
- unaffected 5.10.156 – ≤ 5.10.*
- unaffected 5.15.80 – ≤ 5.15.*
- unaffected 6.0.10 – ≤ 6.0.*
- unaffected 6.1 – ≤ *
References (8)
- https://git.kernel.org/stable/c/0b5e6bd72b8171364616841603a70e4ba9837063 (opens in a new tab)
- https://git.kernel.org/stable/c/9f8554615df668e4bf83294633ee9d232b28ce45 (opens in a new tab)
- https://git.kernel.org/stable/c/7abf40f06a76c0dff42eada10597917e9776fbd4 (opens in a new tab)
- https://git.kernel.org/stable/c/b1ad04da7fe4515e2ce2d5f2dcab3b5b6d45614b (opens in a new tab)
- https://git.kernel.org/stable/c/a8e2fc8f7b41fa9d9ca5f624f4e4d34fce5b40a9 (opens in a new tab)
- https://git.kernel.org/stable/c/0e07032b4b4724b8ad1003698cb81083c1818999 (opens in a new tab)
- https://git.kernel.org/stable/c/5af16182c5639349415118e9e9aecd8355f7a08b (opens in a new tab)
- https://git.kernel.org/stable/c/ef575281b21e9a34dfae544a187c6aac2ae424a9 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://trackcve.app/cve/CVE-2022-49767)Record last updated .